CHECK -> DCHECK to prevent breaking exisitng histograms.

base/metrics/histogram.cc

Index: base/metrics/histogram.cc
===================================================================
--- base/metrics/histogram.cc	(revision 150246)
+++ base/metrics/histogram.cc	(working copy)
@@ -134,7 +134,9 @@
                                  Sample maximum,
                                  size_t bucket_count,
                                  Flags flags) {
-  CHECK(InspectConstructionArguments(name, &minimum, &maximum, &bucket_count));
+  bool valid_arguments =
+      InspectConstructionArguments(name, &minimum, &maximum, &bucket_count);
+  DCHECK(valid_arguments);
 
   Histogram* histogram = StatisticsRecorder::FindHistogram(name);
   if (!histogram) {
@@ -465,9 +467,16 @@
     DVLOG(1) << "Histogram: " << name << " has bad maximum: " << *maximum;
     *maximum = kSampleType_MAX - 1;
   }
+  if (*bucket_count >= kBucketCount_MAX) {
+    DVLOG(1) << "Histogram: " << name << " has bad bucket_count: "
+             << *bucket_count;
+    *bucket_count = kBucketCount_MAX - 1;
+  }
 
-  if (*bucket_count < 3 || *bucket_count >= kBucketCount_MAX)
+  if (*minimum >= *maximum)
     return false;
+  if (*bucket_count < 3)
+    return false;
   if (*bucket_count > static_cast<size_t>(*maximum - *minimum + 2))
     return false;
   return true;
@@ -677,8 +686,9 @@
                                        Sample maximum,
                                        size_t bucket_count,
                                        Flags flags) {
-  CHECK(Histogram::InspectConstructionArguments(name, &minimum, &maximum,
-                                                &bucket_count));
+  bool valid_arguments = Histogram::InspectConstructionArguments(
+      name, &minimum, &maximum, &bucket_count);
+  DCHECK(valid_arguments);
 
   Histogram* histogram = StatisticsRecorder::FindHistogram(name);
   if (!histogram) {